The Boeing Company

Samuel Joseph Cowan

Harry Wilbert Slusher

Belur N Shivashankara

Ronald L Cox

Sunil J Jinadasa

John William Little

Robert P Gerend

James W Ramsay

This invention relates to a hard landing indication system that will provide a quantitative assessment that a hard landing did or did not occur at the last landing of an airplane. A hard landing can cause structural damage to an airplane. An airplane that has been declared to have a hard landing must be grounded until an inspection of the structure has been made to determine if repairs are required.

Airplane hard landing indication system

A gas turbine engine combustion noise suppressor for a jet engine combustor assembly of the annular, cannular, or canannular variety includes a resonant cavity-type or bulk absorber-type noise suppressor. The inner wall of the combustor assembly is configured to couple combustion noise, generated within the burner cavity formed by the inner combustor wall, into the airflow duct formed between the inner and outer walls of the combustor assembly. The outer wall is perforated to, in turn, couple the combustion noise from the airflow duct into the resonant cavity-type or bulk absorber-type noise suppressor that is mounted on the portion of the outer wall that is adjacent the burner cavity. The inner combustor wall can include a large number of small acoustic openings and/or a smaller number of larger openings that include airflow barriers to couple the combustion noise into the combustor airflow duct while simultaneously minimizing air flow into the burner cavity from the combustor airflow duct. In other embodiments, a short burner cavity is employed that includes flutes or corrugations in the inner combustor wall to effect mixing of air and combustion products normally accomplished within the aft section of a conventional burner cavity. In each embodiment the structural relationship between the combustor and the noise suppressor modifies the combustion process occurring within a conventional combustor to generate less noise than a conventional combustor. The noise suppressor functions to further reduce the noise level.

Gas turbine engine combustion noise suppressor

Noise generated by the tips of the fan blades in a turbofan jet propulsion engine is suppressed by generating an annular fluid layer or wake in the inlet of the turbofan engine forwardly from the fan blades and spaced inwardly from the inner wall of the inlet and by lining the inner wall of the inlet with an acoustically absorbent layer of material. Sound waves generated by the fan blades are reflected outwardly by the fluid layer and are absorbed in the acoustic absorbent layer on the inner wall of the inlet. In order for the wake to reflect sound waves, either the local fluid velocity in the wake must be lower than the fluid velocity of the surrounding airstream traveling through the inlet or the acoustic speed in the wake must be greater than or equal to the acoustic speed in the surrounding airstream. It is preferred that both conditions be met. The fluid layer can be created by an annular bluff body positioned in the inlet or by injecting a fluid from an annular plenum in a direction opposite to the flow of the airstream through the inlet.

Fluid layer acoustic shield for turbofan jet propulsion engine

Growing community of inventors

Seattle, WA, United States of America

Samuel Joseph Cowan